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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2006 The Guava Authors<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed under the Apache License, Version 2.0 (the "License");<a name="line.4"></a>
<span class="sourceLineNo">005</span> * you may not use this file except in compliance with the License.<a name="line.5"></a>
<span class="sourceLineNo">006</span> * You may obtain a copy of the License at<a name="line.6"></a>
<span class="sourceLineNo">007</span> *<a name="line.7"></a>
<span class="sourceLineNo">008</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * Unless required by applicable law or agreed to in writing, software<a name="line.10"></a>
<span class="sourceLineNo">011</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.11"></a>
<span class="sourceLineNo">012</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * See the License for the specific language governing permissions and<a name="line.13"></a>
<span class="sourceLineNo">014</span> * limitations under the License.<a name="line.14"></a>
<span class="sourceLineNo">015</span> */<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>package com.google.common.util.concurrent;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import com.google.common.annotations.Beta;<a name="line.19"></a>
<span class="sourceLineNo">020</span><a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.util.concurrent.Callable;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.util.concurrent.TimeUnit;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>/**<a name="line.24"></a>
<span class="sourceLineNo">025</span> * Produces proxies that impose a time limit on method<a name="line.25"></a>
<span class="sourceLineNo">026</span> * calls to the proxied object.  For example, to return the value of<a name="line.26"></a>
<span class="sourceLineNo">027</span> * {@code target.someMethod()}, but substitute {@code DEFAULT_VALUE} if this<a name="line.27"></a>
<span class="sourceLineNo">028</span> * method call takes over 50 ms, you can use this code:<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;pre&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> *   TimeLimiter limiter = . . .;<a name="line.30"></a>
<span class="sourceLineNo">031</span> *   TargetType proxy = limiter.newProxy(<a name="line.31"></a>
<span class="sourceLineNo">032</span> *       target, TargetType.class, 50, TimeUnit.MILLISECONDS);<a name="line.32"></a>
<span class="sourceLineNo">033</span> *   try {<a name="line.33"></a>
<span class="sourceLineNo">034</span> *     return proxy.someMethod();<a name="line.34"></a>
<span class="sourceLineNo">035</span> *   } catch (UncheckedTimeoutException e) {<a name="line.35"></a>
<span class="sourceLineNo">036</span> *     return DEFAULT_VALUE;<a name="line.36"></a>
<span class="sourceLineNo">037</span> *   }<a name="line.37"></a>
<span class="sourceLineNo">038</span> * &lt;/pre&gt;<a name="line.38"></a>
<span class="sourceLineNo">039</span> * Please see {@code SimpleTimeLimiterTest} for more usage examples.<a name="line.39"></a>
<span class="sourceLineNo">040</span> *<a name="line.40"></a>
<span class="sourceLineNo">041</span> * @author Kevin Bourrillion<a name="line.41"></a>
<span class="sourceLineNo">042</span> * @since 1.0<a name="line.42"></a>
<span class="sourceLineNo">043</span> */<a name="line.43"></a>
<span class="sourceLineNo">044</span>@Beta<a name="line.44"></a>
<span class="sourceLineNo">045</span>public interface TimeLimiter {<a name="line.45"></a>
<span class="sourceLineNo">046</span><a name="line.46"></a>
<span class="sourceLineNo">047</span>  /**<a name="line.47"></a>
<span class="sourceLineNo">048</span>   * Returns an instance of {@code interfaceType} that delegates all method<a name="line.48"></a>
<span class="sourceLineNo">049</span>   * calls to the {@code target} object, enforcing the specified time limit on<a name="line.49"></a>
<span class="sourceLineNo">050</span>   * each call.  This time-limited delegation is also performed for calls to<a name="line.50"></a>
<span class="sourceLineNo">051</span>   * {@link Object#equals}, {@link Object#hashCode}, and<a name="line.51"></a>
<span class="sourceLineNo">052</span>   * {@link Object#toString}.<a name="line.52"></a>
<span class="sourceLineNo">053</span>   * &lt;p&gt;<a name="line.53"></a>
<span class="sourceLineNo">054</span>   * If the target method call finishes before the limit is reached, the return<a name="line.54"></a>
<span class="sourceLineNo">055</span>   * value or exception is propagated to the caller exactly as-is. If, on the<a name="line.55"></a>
<span class="sourceLineNo">056</span>   * other hand, the time limit is reached, the proxy will attempt to abort the<a name="line.56"></a>
<span class="sourceLineNo">057</span>   * call to the target, and will throw an {@link UncheckedTimeoutException} to<a name="line.57"></a>
<span class="sourceLineNo">058</span>   * the caller.<a name="line.58"></a>
<span class="sourceLineNo">059</span>   * &lt;p&gt;<a name="line.59"></a>
<span class="sourceLineNo">060</span>   * It is important to note that the primary purpose of the proxy object is to<a name="line.60"></a>
<span class="sourceLineNo">061</span>   * return control to the caller when the timeout elapses; aborting the target<a name="line.61"></a>
<span class="sourceLineNo">062</span>   * method call is of secondary concern.  The particular nature and strength<a name="line.62"></a>
<span class="sourceLineNo">063</span>   * of the guarantees made by the proxy is implementation-dependent.  However,<a name="line.63"></a>
<span class="sourceLineNo">064</span>   * it is important that each of the methods on the target object behaves<a name="line.64"></a>
<span class="sourceLineNo">065</span>   * appropriately when its thread is interrupted.<a name="line.65"></a>
<span class="sourceLineNo">066</span>   *<a name="line.66"></a>
<span class="sourceLineNo">067</span>   * @param target the object to proxy<a name="line.67"></a>
<span class="sourceLineNo">068</span>   * @param interfaceType the interface you wish the returned proxy to<a name="line.68"></a>
<span class="sourceLineNo">069</span>   *     implement<a name="line.69"></a>
<span class="sourceLineNo">070</span>   * @param timeoutDuration with timeoutUnit, the maximum length of time that<a name="line.70"></a>
<span class="sourceLineNo">071</span>   *     callers are willing to wait on each method call to the proxy<a name="line.71"></a>
<span class="sourceLineNo">072</span>   * @param timeoutUnit with timeoutDuration, the maximum length of time that<a name="line.72"></a>
<span class="sourceLineNo">073</span>   *     callers are willing to wait on each method call to the proxy<a name="line.73"></a>
<span class="sourceLineNo">074</span>   * @return a time-limiting proxy<a name="line.74"></a>
<span class="sourceLineNo">075</span>   * @throws IllegalArgumentException if {@code interfaceType} is a regular<a name="line.75"></a>
<span class="sourceLineNo">076</span>   *     class, enum, or annotation type, rather than an interface<a name="line.76"></a>
<span class="sourceLineNo">077</span>   */<a name="line.77"></a>
<span class="sourceLineNo">078</span>  &lt;T&gt; T newProxy(T target, Class&lt;T&gt; interfaceType,<a name="line.78"></a>
<span class="sourceLineNo">079</span>      long timeoutDuration, TimeUnit timeoutUnit);<a name="line.79"></a>
<span class="sourceLineNo">080</span><a name="line.80"></a>
<span class="sourceLineNo">081</span>  /**<a name="line.81"></a>
<span class="sourceLineNo">082</span>   * Invokes a specified Callable, timing out after the specified time limit.<a name="line.82"></a>
<span class="sourceLineNo">083</span>   * If the target method call finished before the limit is reached, the return<a name="line.83"></a>
<span class="sourceLineNo">084</span>   * value or exception is propagated to the caller exactly as-is.  If, on the<a name="line.84"></a>
<span class="sourceLineNo">085</span>   * other hand, the time limit is reached, we attempt to abort the call to the<a name="line.85"></a>
<span class="sourceLineNo">086</span>   * target, and throw an {@link UncheckedTimeoutException} to the caller.<a name="line.86"></a>
<span class="sourceLineNo">087</span>   * &lt;p&gt;<a name="line.87"></a>
<span class="sourceLineNo">088</span>   * &lt;b&gt;Warning:&lt;/b&gt; The future of this method is in doubt.  It may be nuked, or<a name="line.88"></a>
<span class="sourceLineNo">089</span>   * changed significantly.<a name="line.89"></a>
<span class="sourceLineNo">090</span>   *<a name="line.90"></a>
<span class="sourceLineNo">091</span>   * @param callable the Callable to execute<a name="line.91"></a>
<span class="sourceLineNo">092</span>   * @param timeoutDuration with timeoutUnit, the maximum length of time to wait<a name="line.92"></a>
<span class="sourceLineNo">093</span>   * @param timeoutUnit with timeoutDuration, the maximum length of time to wait<a name="line.93"></a>
<span class="sourceLineNo">094</span>   * @param interruptible whether to respond to thread interruption by aborting<a name="line.94"></a>
<span class="sourceLineNo">095</span>   *     the operation and throwing InterruptedException; if false, the<a name="line.95"></a>
<span class="sourceLineNo">096</span>   *     operation is allowed to complete or time out, and the current thread's<a name="line.96"></a>
<span class="sourceLineNo">097</span>   *     interrupt status is re-asserted.<a name="line.97"></a>
<span class="sourceLineNo">098</span>   * @return the result returned by the Callable<a name="line.98"></a>
<span class="sourceLineNo">099</span>   * @throws InterruptedException if {@code interruptible} is true and our<a name="line.99"></a>
<span class="sourceLineNo">100</span>   *     thread is interrupted during execution<a name="line.100"></a>
<span class="sourceLineNo">101</span>   * @throws UncheckedTimeoutException if the time limit is reached<a name="line.101"></a>
<span class="sourceLineNo">102</span>   * @throws Exception<a name="line.102"></a>
<span class="sourceLineNo">103</span>   */<a name="line.103"></a>
<span class="sourceLineNo">104</span>  &lt;T&gt; T callWithTimeout(Callable&lt;T&gt; callable, long timeoutDuration,<a name="line.104"></a>
<span class="sourceLineNo">105</span>      TimeUnit timeoutUnit, boolean interruptible) throws Exception;<a name="line.105"></a>
<span class="sourceLineNo">106</span>}<a name="line.106"></a>




























































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